Risks of urgent cesarean delivery preceding the planned schedule: A retrospective cohort study

Purpose The aim of the study was to ascertain risk factors and outcomes of elective cesarean deliveries performed urgently prior to their scheduled date. Methods Women carrying a viable singleton fetus who were scheduled for elective cesarean delivery at a tertiary medical center between 2012–2020 were identified by retrospective database. Differences in maternal and neonatal parameters between those who ultimately required urgent cesarean delivery and those who underwent the procedure as scheduled were analyzed. Results Of 4403 women who met the inclusion criteria, 559 underwent urgent cesarean delivery before the scheduled date. On multivariate analysis, factors significantly associated with a risk of transformation to an urgent cesarean delivery were chronic hypertension (aOR 1.92, 95% CI 1.30–2.83 P = 0.001), antenatal corticosteroids administration (aOR 3.26, 95% CI 2.38–4.47, P <0.001), and contraindication for vaginal delivery as the reason for elective cesarean delivery (aOR 1.67, 95% CI 1.32–2.12, P <0.001). Neonates born via urgent cesareans had an increased risk of 1-minute Apgar <7 (6% vs. 1.7%, P <0.001), intensive care unit admission (6.6% vs. 2.5%, P <0.001); their mothers were at risk of postpartum hemorrhage (5.9% vs. 3%, P = 0.001). Conclusions The present study sheds light on the risk factors and maternal and fetal morbidities associated with elective cesarean deliveries that become urgent before the originally scheduled date. Physicians should take this information into account when planning an optimal date for elective cesarean delivery.


Introduction
Cesarean delivery (CD) is one of the most prevalent surgical procedures performed worldwide. In recent years, the rate of CD has almost doubled [1,2] with studies in the United States reporting an increase from 16 million births in 2000 to 29.7 million in 2015 [3].
Urgent CDs are performed in the presence of various concerning indications such as nonreassuring fetal heart rate, labor dystocia, or cephalopelvic disproportion, where continuation of pregnancy may jeopardize maternal and neonatal outcomes [4][5][6]. Planned elective CD is recommended when it is likely to provide a better maternal or fetal outcome than vaginal delivery [4]. Accepted medical and obstetrical indications for elective CD include past cesarean delivery, fetal malpresentation, and multiple gestation, although indications may slightly differ according to local national guidelines.
When scheduling an elective CD, physicians need to carefully weigh the maternal and neonatal risks and benefits. On the one hand, CD is best performed at late term when neonatal complications are low [7][8][9][10]. Studies have shown that the risk of respiratory distress syndrome and transient tachypnea of the newborn decreases as gestational age of planned CD increases from 37 to 40 weeks [11][12][13][14]. On the other hand, elective CD should be done as early as possible to avoid the onset of spontaneous labor which would necessitate unscheduled urgent CD. Maternal morbidity is higher in urgent than in elective CD due to pelvic organ injury, hemorrhage, need for blood transfusions, wound site complications, and longer hospitalization [15,16]. The National Institute of Health and Care Excellence and the American College of Obstetricians and Gynecologists recommend scheduling elective CD at 39-40 gestational weeks unless there is an obstetric or medical indication for earlier delivery [17,18].
Numerous studies have examined the indications and outcomes of planned and elective CDs. However, factors that play a role when a CD that was preplanned becomes urgent have hardly been investigated. The aim of this study was to ascertain the risks, indications, and maternal-neonatal outcomes of elective CDs that precede their original scheduled date in order to identify the patient group that may require more careful planning.

Design and patients
A retrospective cohort design was used. The database of a university-affiliated tertiary medical center was searched for all women carrying a viable singleton fetus who were scheduled for elective CD between July 2012 and December 2020. Women who had a vaginal delivery, late abortion, or preterm birth (before 24 gestational weeks) were excluded as were women with a fetus with congenital anomalies or multiple gestation or who underwent elective CD prior to 37 or later than 40 gestational weeks. The women eligible for the study were divided into two groups: those who underwent urgent CD before the preplanned CD date and those who underwent planned elective CD as scheduled (controls).

Data collection
Maternal, obstetric, surgical, and neonatal parameters were derived from the department's comprehensive electronic medical records as follows: maternal age, height, and weight; gravidity, parity, use of assisted reproductive techniques (ART), and previous CD; pregnancy complications such as hypertensive disorders in pregnancy, diabetes mellitus in pregnancy (type 1, type 2 or gestational), antenatal corticosteroids administration, adherent placenta, and placenta previa; intrapartum characteristics including indications for planned and urgent CD, type of anesthesia, duration of surgery, and number of days between scheduled and actual delivery dates; intraoperative and postoperative complications such as intra-abdominal adhesions, bladder lacerations, uterine scar dehiscence or rupture, cesarean hysterectomy, postpartum hemorrhage, surgical site infection, paralytic ileus and number of hospitalization days. For women who underwent urgent CD ahead of the planned date, the indications leading to the pre-scheduled CD were categorized as term or preterm premature rupture of membranes (PROM or PPROM), preterm contractions and cervical dynamics, non-reassuring fetal heart rate (NRFHR), chorioamnionitis, and placental abruption. Neonatal outcome parameters included gestational age at birth, birthweight, 1-and 5-min Apgar scores, umbilical cord blood pH, and neonatal intensive care unit (NICU) admission.

Definitions
Gestational age was determined by the last menstrual period and affirmed by crown-rump length measurement on the first-trimester ultrasound scan. Small for gestational age was defined as birthweight below the 10th percentile according to nationally accepted birthweight reference curves [19].
Elective planned CD was defined as CD performed prior to the expected due date for any of the following indications: 1) past uterine surgery, 2) relative or absolute contraindications for vaginal birth, including malpresentation, suspected macrosomia, fetal growth restriction, labial herpes virus infection, maternal request; (3) others, such as maternal orthopedic/ophthalmic medical conditions. At our institution, elective CD is scheduled in a pre-op ambulatory meeting held 8-10 weeks before the accepted due date, after review of the full patient history and results of physical examination and antenatal follow up. First or second CDs are usually scheduled for 39 gestational weeks, according to accepted guidelines [17,18]; third or more CDs are scheduled for 38-39 gestational weeks. In cases of placenta previa, previous uterine surgeries, or prior intrauterine fetal death, elective CD is routinely scheduled for 37-38 gestational weeks.

Outcome measures
The main outcome of the study was to identify factors associated with early performance of elective CD, before the scheduled date. Secondary outcome measures were maternal and neonatal outcomes of urgent CD in this setting.

Ethical approval
Research involving human subjects complied with all relevant national regulations, institutional policies and is in accordance with the tenets of the Helsinki Declaration (as revised in 2013), and has been approved by the authors' Institutional Review Board (Rabin Medical Center Helsinki Review Board, approval no. 0087-21-RMC), with waiver of informed consent due to the retrospective, observational design of the study.

Statistical analysis
Statistical analysis was performed with SAS version 9.4 (Cary, NC, USA). Continuous variables were compared between groups using the general linear model (GLM); chi-square and Fisher's exact tests were used for categorical variables, as appropriate. Differences were considered significant when p was less than 0.05. To identify factors affecting the risk of pre-scheduled performance of elective CD, multivariate analysis was used, adjusted for confounders.

Results
Of the 6177 women who were scheduled for a planned CD during the study period, 1774 were excluded for the following reasons (Fig 1): CD scheduled for earlier than 37 gestational weeks (n = 801) or after 40 gestational weeks (n = 109), insufficient data (n = 593), major fetal anomalies (n = 205), urgent CD performed after the scheduled date (n = 33), multiple gestation with or without selective fetal reduction (n = 18), and CD due to failed induction (n = 15). The remaining 4403 women formed the final cohort, of whom 559 (13%) had an urgent CD preceding the planned schedule and 3844 (87%) underwent the procedure as scheduled (control group). The final cohort included women carrying a viable singleton fetus who were scheduled for an elective CD between 37 to 40 weeks.
Postpartum maternal and neonatal outcomes are shown in Table 3. Compared to controls, the urgent-CD group had higher rates of postpartum hemorrhage (5.9% vs 3.0%, P = 0.001), blood transfusions (2.5% vs. 1.1% P = 0.012), magnesium administration (3.2% vs 0.6%,  an aOR of 1.67 (CI 1.32-2.12, P <0.001) for undergoing urgent CD. Maternal age, ART, gestational and pregestational diabetes in pregnancy, and nulliparity were no longer significant. Stratifying the gestational age at which CD was planned by indication revealed that women with previous uterine surgery were scheduled for elective CD at an earlier median gestational age than women with a contraindication for vaginal delivery (38+1±0.64 vs 38+4±0.66 weeks, respectively, P<0.001). Women with two or more past CDs were scheduled for CD at an even earlier gestational age (38+0±0.59 weeks).

Discussion
This study sought to characterize the population of women who are scheduled for elective CD but undergo urgent CD before the planned date. Our key findings were as follows: (1) Chronic hypertension, antenatal corticosteroids administration, and a contraindication for vaginal delivery were risk factors for urgent CD. (2) Rates of postpartum hemorrhage, magnesium administration, NICU admission and 1-minute Apgar <7 were all significantly higher in the urgent-CD group. (3) The most common indications for urgent CD were contractions (42.6%) and PROM/ PPROM (30.0%), (4) The median interval between planned and urgent CD was 5 days (0-51), and the median gestational age at which elective CD was scheduled was 38+2 weeks (37)(38)(39)(40).
The optimal gestational age for a planned CD is a product of the maternal-neonatal balance between the possibility of preterm or early term morbidity and the possibility of urgent CD. Current recommendations [17] discourage non-indicated delivery before 39 gestational weeks because of its well established association with potential neonatal complications [14,20]. However, some studies have shown that women who were scheduled for elective CD at 39 weeks were more likely than women scheduled for elective CD at 38 gestational weeks to require urgent CD [21,22], placing them at increased risk of both maternal and fetal complications [23][24][25][26][27]. Overall, rates of transformation from planned to urgent CD in the literature range from 13% to 16% for CDs scheduled for 38 gestational weeks to 23% to 51% for CDs scheduled for 39 gestational weeks [21,28,29]. These values agree with the overall risk of 13% in our study, in which the median gestational age for planned CD was 38+3 weeks (37 to 40).
Chronic hypertension as well as hypertensive disorders of pregnancy were significantly more common among women in the urgent CD group. Hypertension by itself, in women without an indication for CD, has not been shown in previous studies to be a risk factor for CD. However, chronic hypertension is an established risk factor for preeclampsia [30,31], one of many hypertensive disorders in pregnancy that are often managed by delivery. In these cases, delivery is by urgent CD when the disorder occurs at an early gestational age in patients with an unfavorable cervix or with a contraindication for vaginal delivery.
Women treated with antenatal corticosteroids were 3.2 times more likely to undergo urgent CD (OR 3.2, CI 2.4-4.5, Table 4). There are several possible explanations for this finding. First, studies have reported a significant decrease in the neonatal complication rate following antenatal corticosteroids treatment [32,33], which makes it easier for the attending physician to decide on earlier delivery. Second, the very administration of antenatal corticosteroids indicates an underlying condition in which delivery, either spontaneous or iatrogenic, may be imminent. Hence, in women who have already received antenatal corticosteroids, the probability of there being an indication for urgent delivery is higher.
The indications for which the women were initially referred for elective CD varied. More women in the urgent-CD than the control group were scheduled for elective CD because of a contraindication for vaginal delivery. The odds ratio for undergoing urgent CD among women with a contraindication for vaginal delivery was 1.67 (95% CI 1.32-2.12, P<0.05) ( Table 4). Some of the reasons for ruling out vaginal delivery, such as placenta previa, fetal growth restriction [34,35], and malpresentation accompanied by PROM or /PPROM, are also independent risk factors for urgent CD.
Studies have shown that women with a history of multiple CDs are more likely to have adhesions and associated surgical complications [36][37][38]. Although 39 weeks has usually been reported as the optimal time for elective CD, there is some evidence that in women after two or more cesarean sections, the risk of maternal adverse outcome is higher for planned CD at 39 weeks compared to 38 weeks [21,28]. Therefore, even in the absence of a clearcut indication for an earlier delivery there may be a tendency among physicians to schedule CD in these cases at an earlier gestational age to lower the chance of labor onset ahead of the schedule. If medically possible, in patients who present at odd hours, they are also likely to postpone these complex surgical procedures to the daytime when more experienced surgeons are available.
Neonates born via urgent CD had an increased risk of a 1-minute Apgar score <7 and of NICU admission. Mothers undergoing urgent CD had a higher risk for postpartum hemorrhage. These findings are supported by previous studies which showed poorer maternal and neonatal outcomes in urgent versus elective CDs [23][24][25][26][27][39][40][41].
This study was limited by the retrospective design and the selection bias resulting from our policy to schedule CDs earlier in more surgically complex cases, lowering the chances that these women would enter spontaneous labor. The classification of indications for CD is debatable, as some indications include various groups in them. In addition, data on infant longterm outcome were lacking. The main strengths of the study were the inclusion of two population groups attending a single-center with uniform treatment protocols. Moreover, the large sample size was sufficient to detect significant differences in maternal and neonatal complications between the groups, such that we were able to investigate an issue that has not been previously addressed in the literature.

Conclusion
To our knowledge, this is the first study to examine risk factors for urgent CD in women scheduled for elective CD. Significant risk factors for urgent CD were chronic hypertension, antenatal corticosteroids administration, and a contraindication for vaginal delivery as the reason for scheduling an elective CD. The timing of elective CD is based on a balance between maternal and neonatal factors and is set optimally in the majority of cases at 39 gestational weeks. However, in several subgroups of women who are prone to earlier delivery, an earlier gestational age might be considered.